Re: [PATCH v2] nfs: add dummy definition for nfsd_file

[Jeff Layton <jlayton@kernel.org>]

On Wed, 2025-04-09 at 22:09 -0400, Mike Snitzer wrote:
> Add dummy definition for nfsd_file in both nfslocalio.c and localio.c
> so various compilers (e.g. gcc 8.5.0 and 9.5.0) can be used. Otherwise
> RCU code (rcu_dereference and rcu_access_pointer) will dereference
> what should just be an opaque pointer (by using typeof(*ptr)).
> 
> Fixes: 86e00412254a ("nfs: cache all open LOCALIO nfsd_file(s) in client")
> Cc: stable@vger.kernel.org
> Tested-by: Jeff Johnson <jeff.johnson@oss.qualcomm.com>
> Tested-by: Pali Rohár <pali@kernel.org>
> Tested-by: Vincent Mailhol <mailhol.vincent@wanadoo.fr>
> Signed-off-by: Mike Snitzer <snitzer@kernel.org>
> ---
>  fs/nfs/localio.c           | 8 ++++++++
>  fs/nfs_common/nfslocalio.c | 8 ++++++++
>  2 files changed, 16 insertions(+)
> 
> v2: fix email used in S-o-B, added 3 Tested-by:s and adjust commit header.
> 
> diff --git a/fs/nfs/localio.c b/fs/nfs/localio.c
> index 5c21caeae075..830078e5866b 100644
> --- a/fs/nfs/localio.c
> +++ b/fs/nfs/localio.c
> @@ -46,6 +46,14 @@ struct nfs_local_fsync_ctx {
>  	struct completion	*done;
>  };
>  
> +/*
> + * nfsd_file structure is purposely kept opaque to NFS client.
> + * This is a dummy definition to make RCU compilation happy.
> + */
> +struct nfsd_file {
> +	int undefined__;
> +};
> +
>  static bool localio_enabled __read_mostly = true;
>  module_param(localio_enabled, bool, 0644);
>  
> diff --git a/fs/nfs_common/nfslocalio.c b/fs/nfs_common/nfslocalio.c
> index 6a0bdea6d644..f3274a70ce5e 100644
> --- a/fs/nfs_common/nfslocalio.c
> +++ b/fs/nfs_common/nfslocalio.c
> @@ -271,6 +271,14 @@ struct nfsd_file *nfs_open_local_fh(nfs_uuid_t *uuid,
>  }
>  EXPORT_SYMBOL_GPL(nfs_open_local_fh);
>  
> +/*
> + * nfsd_file structure is purposely kept opaque to NFS client.
> + * This is a dummy definition to make RCU compilation happy.
> + */
> +struct nfsd_file {
> +	int undefined__;
> +};
> +
>  void nfs_close_local_fh(struct nfs_file_localio *nfl)
>  {
>  	struct nfsd_file *ro_nf = NULL;

Acked-by: Jeff Layton <jlayton@kernel.org>